目前直接探测PM_2.5质量浓度高度廓线有一定的困难,但可以通过一定的关系把激光雷达探测出的气溶胶后向散射系数高度廓线转化为PM_2.5质量浓度高度廓线。在把气溶胶后向散射系数廓线转化为PM_2.5质量浓度的过程中,气溶胶吸湿因子是一个关键的参数。激光雷达系统可探测气溶胶后向散射系数在近地面的高度分布廓线,PM_2.5质量探测仪可探测所在处的PM_2.5质量浓度和大气相对湿度。将这两种仪器置于同一地点同时进行探测,以获取同一地点同一时间的气溶胶后向散射系数、PM_2.5质量浓度和大气相对湿度。在理论的指导下对所探测的数据进行拟合,可得出吸湿因子的表达式。对2016年5月—2017年10月合肥地区仪器所在地的气溶胶后向散射系数、PM_2.5质量浓度和大气相对湿度的探测数据进行拟合,获得了PM_2.5质量浓度与气溶胶后向散射系数之间吸湿因子的变化规律。

At present, the height profile of PM2.5 mass concentration is difficult to detect directly. However, a certain relationship can be used to transfer the height profile of aerosol backscattering coefficient detected by lidar to the height profile of PM2.5 mass concentration. The hygroscopic factor of aerosol is a key parameter in the process of transferring the profile of aerosol backscattering coefficient to that of PM2.5 mass concentration. The near ground height distribution profile of aerosol backscattering coefficient can be detected by the lidar system, while the PM2.5 mass concentration and atmospheric relative humidity are measured by PM2.5 monitor. The two instruments are placed at the same location and probed simultaneously to obtain the aerosol backscattering coefficient, PM2.5 mass concentration and atmospheric relative humidity at the same time. Under the guidance of the theory, the expression hygroscopic factor is calculated by fitting the related experimental data. By fitting the detection data aerosol backscattering coefficient, PM2.5 mass concentration and atmospheric relative humidity in Hefei area from May 2016 to October 2017, the change law of the hygroscopic factor between PM2.5 mass concentration and aerosol backscattering coefficient is obtained.